820-00840 - thunderbolt peripherals isnt working on the USB-C port (B)


charging is working on both ports, USB thumb & 2.5" external drives is working both ports.
but when i try plugging a Belkin thunderbolt ethernet adapter that is closer to the screen hinge isn't working. however, the top port is working with the thunderbolt ethernet adapter.
same when i use an apple multiport digital adapter.

i don't have another 820-00840 so i don't have one to compare measurement.

any idea. thanks

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I've replaced u3200, it's still the same.

then i went ahead removed the shield :

found a blown D3414 diode

I've removed this ESD protection diode, it's still not working.

top port still works



found OL in diode mode on XB_D2R_CONN_N (should be getting around 0.344v)

R3476 is 0hm so its good.

so either USBC_XB_D2R_N to U2800 trace is bad or U2800 is bad.
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Staff member
If D3414 was the burnt ESD diode, then likely bad U2800.
If no need to use both ports at same time, leave it as is.
Recommend an USB-C hub to the client, just in case.